17.4.2: Infertility in farm species Flashcards
What are the 3 broad presentations of infertility?
- Cycling animals do not conceive i.e. ovulating but not being fertilised
- Animals that are not/do not appear to be cycling at all
- Animals that conceive but do not maintain pregnancy
What are the possible causes of cycling cows not conceiving?
- Improper/incorrect insemination
- Infectious causes
- Toxins
- Metabolic/nutritional causes
- Iatrogenic causes
- Sire choice
What are some possible reasons why cows may not cycle?
- False anoestrus: oestrus not observed/recognised
- Metabolic/nutritional cause e.g. NEB
- Uterine infection
- Pregnancy
- Cystic ovarian disease
- Suckling calf at foot
What are some possible viral causes of infectious infertility in cattle and sheep?
- BVD
- Border disease
- IBR (BoHV-1)
What are some bacterial and protozoal infectious causes of infertility?
- Leptospira
- Brucella
- Campylobacter
- Tritrichomonas
What are the effects and presentation of BVD with regard to fertility?
- Effects: early embryonic death and ovarian damage
- Presentation: long returns to service (25-35 days) and reduced conception rate
- This has a huge economic impact!
What are the effects and presentation of Border Disease Virus in sheep and goats with regard to fertility?
- Effects: Poor fertility
- Presentation: Increased barren rate
What are the effects and presentation of IBR with regards to infertility?
- Effects; temporary ovarian necrosis, follicular degeneration
- Presentation: reduced conception rate due to reduced ovulation capacity and reduced oocyte viability
Describe the effects and presentation of Leptospira in cattle with regards to fertility
- Effects: poor fertility and EED, possibly due to endometrial inflammation but unknown
- Presentation: reduced conception rates and long returns to service (25-35d)
Describe the effects and presentation of Brucella in cattle with regards to fertility
- Effects: poor fertility, epididymitis and orchitis
- Presentation: reduced concept rates in cattle / increased barren rates in sheep
- Notifiable and zoonotic!
Describe the effects and presentation of Campylobacter with regards to fertility
- Effects: endometritis (cattle), failure to conceivem early embryonic death (cattle), abortion (sheep and cattke)
- Effects: irregular oestrus cycles, repeat breedings -> long calving intervals, long returns to service, high returns to oestrus. Visible abortion.
Describe the effects and presentation of Tritrichomonas in cattle with regards to fertility
- Effects: early embryonic death, pyometra, endometritis
- Presentation: long returns to service (25-35d), identified on clinical exam
- Protozoal cause, more of an issue in herds using natural service
If GnRH is given at the start of oestrus, what is the effect?
Ovulation in 24-48hrs
* GnRH stimulates the release of FSH and LH and so induces ovulation
If GnRH is given 10-12 days post-oestrus, what is the effect?
- Reinforces CL action -> aids maintenance of pregnance
- Used to be used to help a cow keep a doubtful pregnancy - not done so much now
When do prostaglandins have an effect on the ovary and how?
- Prostaglandins cause luteolysis of the CL
- The CL will only respond from day 5-15 of pregnancy
- CL will be over >17 mm on ultrasound
What are prostaglandins used for?
- Synch protocols
- Treatment of luteal cysts
- Induce abortion or parturition
- Treat pyometra
- Control of breeding and oestrus timing
What could you use to treat follicular cysts?
GnRH
Buserelin
GnRH analogue
Gonadorelin
synthetic GnRH
Dinoprost
PGF2a
Cloprostenol
Synthetic PGF2a analogue
True/false: progesterone can be used to improve oocyte quality
True
How can progesterone be used with relation to ovulation?
- Progesterone e.g. PRID, CIDR acts as exogenous CL
- This suppresses GnRH
- A dominant follicle may develop but will not ovulate
- When the progesterone-releasing device is removed, there is an LH surge which causes ovulation
What complications can you see with progesterone devices?
- Necrosis at points of T where in contact with vaginal wall - tends to self-resolve
- Vaginitis, purulent discharge - self-resolves with removal and does not require treatment
- May need to cut device tail short in heifers who pull them out - take care to ensure the devices will not be left in accidentally
How would you create a teaser bull?
- Epididymectomy is easier and safer than vasectomy because it can be done standing (compared to vasectomy which requires dorsal recumbency)
- Penile alterations not done in UK
What is your diagnosis and what structure would you expect on the ovary? How will you treat this cow?
Diagnosis: pyometra
Expected ovarian structure: CL
Treatment: PGF2a; if a long standing pyo of 5-6+ months, will need to cull
Diagnosis and treatment?
Follicular cyst
Can force ovulation with GnRH/ PRID/ both
Do not serve to this forced ovulation - the oocyte will be ancient and poor quality so conception rate likely to be poor
Diagnosis?
- This cow has either just ovulated or may be in anoestrus
- There are tiny follicles less than 0.5cm in diameter
- There is no luteal tissue
- This ovary is not cycling but need to check the other one
- Need more history/ questions to work out if she has just ovulated or requires treatment e.g. GnRH / progesterone for anoestrus
